In a conventional motion transforming mechanism for converting rotating into reciprocating motion, an objective which is encountered in small printing machines, the sliding portion of the mechanism which is responsible for advancement of the paper on which text is to be printed consists of a paper-feeding lever, a rack lever which makes contact with a rotating pinion gear and a trigger portion which is moved by an electromagnet. In addition, this portion of the mechanism requires three springs which are used to return the sliding portion of the mechanism to a normal position in which the rack is disengaged from the pinion.
The trigger portion of the mechanism must engage a notch in the rack lever as the sliding mechanism is pulled back into normal position, else the system will fail to function when the electromagnet is pulsed.
The conventional mechanism is unnecessarily complex because of the fact that the sliding portion of the mechanism involves at least three portions in addition to the springs. Further, the engagement of the trigger portion with the notch in the rack lever is uncertain so that it may happen that the rack lever engages the gear at inappropriate moments during operation of the system. Also, the system is not suitable for miniaturization because of the number of members involved in carrying out the necessary operations. Finally, start-up may be difficult because the trigger portion is disengaged from the electromagnet abruptly and the rack lever may become engaged with the gear which holds a print drum.